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[PATCH v10 2/2] handle relation statistics correctly during rewrites 571+ messages / 2 participants [nested] [flat]
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v8 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index ee6f2eb2bdb..83103189fb5 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index c9e451094f3..33d530740d0 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --BHD/2LBqtxMXWADJ-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v9 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 48bf93cae6e..b6ba8fdf440 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3451538565e..0ca3eae8026 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2268,6 +2268,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --tV2Nti+lXhoeT6I5-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v10 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8dea58ad96b..b71925a22c3 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 2120c85ccb4..6155b12afab 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 6b1a00ed477..9de70f321ed 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16884,6 +16884,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16922,6 +16923,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16934,6 +16936,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index a267e93f8be..123fb50d98f 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 2d0cb7bcfd4..c98e5c51d63 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 3102f86aa24..8750c025bbe 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -670,7 +670,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -682,6 +682,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 04845d5e680..3184e9c464b 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2269,6 +2269,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --xJsrX25x3tm7Tn81-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v11 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index df1ba112b35..6244d04ab12 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16896,6 +16896,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16934,6 +16935,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16946,6 +16948,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 6b634c9fff1..692d084acb2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index e9e4d32c3b8..a9a4fa9f8f2 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -669,7 +669,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -681,6 +681,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 241945734ec..05b1380c08c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2279,6 +2279,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --zLA8DXafBEP889wv-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v12 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 43de42ce39e..88ef00609db 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1793,7 +1793,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 60a4617a585..3a446f32921 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 85242dcc245..8d10d9d1e0f 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16883,6 +16883,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16921,6 +16922,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16933,6 +16935,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index a1c88c6b1b6..dc5948f446c 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3775,6 +3776,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3946,6 +3948,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3250564d4ff..fbcbe5da26a 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2281,6 +2281,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --sdA5zuaL94ts0rne-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v13 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 8b3c60d91f9..7c7d0fb8e7a 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 67e42e5df29..1715af2c0d8 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 3a4f19e8d58..60491962668 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -86,6 +86,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3771,6 +3772,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3942,6 +3944,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 689c624f373..d0d5473f8a5 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -673,7 +673,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -685,6 +685,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 52f8603a7be..8b84e3a0bcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2298,6 +2298,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --USlF2Vr25us5UpvY-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v14 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index d8219b18c48..079e504b96f 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c69c12dc014..13630846116 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17099,6 +17099,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17137,6 +17138,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17149,6 +17151,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index dbbec84b222..bae04e95989 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2310,6 +2310,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --96iU9DKeu+W+YlSa-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v15 2/2] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 1ccfa687f05..e292199ca7c 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1796,7 +1796,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index 09066db0956..c491daceb0f 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1206,6 +1206,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 8b4ebc6f226..49de04d9697 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17102,6 +17102,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17140,6 +17141,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17152,6 +17154,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 89bf0cbed56..4d929972fab 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +223,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +313,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -666,6 +788,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -681,6 +845,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -760,11 +948,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -784,10 +980,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -810,6 +1079,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -845,6 +1116,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -859,9 +1153,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -916,7 +1227,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1167,3 +1488,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index e19f0d3e51c..bf49830dba2 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3772,6 +3773,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3943,6 +3945,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index ef740aff26e..4d3130ae99e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -701,7 +701,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -713,6 +713,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index c9da1f91cb9..53c94382a8d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2314,6 +2314,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Og8T0Lf2JVsuKOzn-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v7 3/3] handle relation statistics correctly during rewrites @ 2025-11-04 13:52 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw) Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites. To do so, this patch: - Adds PgStat_PendingRewrite, a new struct to track rewrite operations within a transaction, storing the old locator, new locator, and original locator (for rewrite chains). This allows stats to be copied from the original location to the final location at commit time. - Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins. It records the rewrite operation in a local list and detects rewrite chains by checking if the old_locator matches any existing new_locator, preserving the chain's original_locator. - Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of Relations, with a new increment parameter to accumulate stats (needed for rewrite chains with DML between rewrites). - Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(), pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the PgStat_PendingRewrite list correctly. Note that due to the new flush call in pgstat_twophase_postcommit() we can not call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So, adding a check to handle this special case and call GetCurrentTimestamp() instead. Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that the GetCurrentTimestamp() extra cost should be negligible. Another solution could be to trigger the flush from FinishPreparedTransaction() but that's not worth the extra complexity. The new pending_rewrites list is traversed in multiple places. The overhead should be negligible in comparison to a rewrite and the list should not contain a lot of rewrites in practice. The pending_rewrites list is traversed in multiple places. In typical usage, the list will contain only a few entries so the traversal cost is negligible ( furthermore in comparison to a rewrite). --- src/backend/catalog/index.c | 2 +- src/backend/commands/cluster.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 424 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.9% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 5d9db167e59..8b6a7652fcf 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1795,7 +1795,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index b55221d44cd..da75dfa6ab8 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1196,6 +1196,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3aac459e483..540923452fb 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -16848,6 +16848,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -16886,6 +16887,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -16898,6 +16900,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7debb14bb5d..15b4663eb77 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,70 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src)); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src)); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +194,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -165,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -215,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -660,6 +782,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -675,6 +839,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -754,11 +942,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -778,10 +974,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -804,6 +1073,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -839,6 +1110,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -853,9 +1147,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -910,7 +1221,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1162,3 +1483,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index bc9864bd8d9..f8cf3755ce2 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 915d0bc9084..7a7f8023eb3 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -85,6 +85,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3780,6 +3781,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3951,6 +3953,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 5d0fe79f7e3..332dffde400 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -665,7 +665,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -677,6 +677,9 @@ extern void pgstat_report_vacuum(RelFileLocator locator, PgStat_Counter livetupl extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 432509277c9..bd8fcb16dcf 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2248,6 +2248,7 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --KMYjwlsACqdYx2P8-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v2 2/4] pg_upgrade: bump minimum supported version to v10 @ 2026-04-17 18:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Nathan Bossart @ 2026-04-17 18:20 UTC (permalink / raw) --- doc/src/sgml/ref/pgupgrade.sgml | 2 +- src/bin/pg_upgrade/check.c | 157 +---------------------- src/bin/pg_upgrade/controldata.c | 12 +- src/bin/pg_upgrade/exec.c | 23 ---- src/bin/pg_upgrade/file.c | 164 ------------------------- src/bin/pg_upgrade/multixact_rewrite.c | 11 +- src/bin/pg_upgrade/pg_upgrade.c | 31 +---- src/bin/pg_upgrade/pg_upgrade.h | 29 ----- src/bin/pg_upgrade/relfilenumber.c | 37 +----- src/bin/pg_upgrade/version.c | 127 ------------------- 10 files changed, 16 insertions(+), 577 deletions(-) diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml index 38ca09b423c..c4ed75211db 100644 --- a/doc/src/sgml/ref/pgupgrade.sgml +++ b/doc/src/sgml/ref/pgupgrade.sgml @@ -67,7 +67,7 @@ PostgreSQL documentation </para> <para> - <application>pg_upgrade</application> supports upgrades from 9.2.X and later to the current + <application>pg_upgrade</application> supports upgrades from 10.X and later to the current major release of <productname>PostgreSQL</productname>, including snapshot and beta releases. </para> diff --git a/src/bin/pg_upgrade/check.c b/src/bin/pg_upgrade/check.c index 5a7afe62eab..0813cef2729 100644 --- a/src/bin/pg_upgrade/check.c +++ b/src/bin/pg_upgrade/check.c @@ -28,7 +28,6 @@ static void check_for_incompatible_polymorphics(ClusterInfo *cluster); static void check_for_tables_with_oids(ClusterInfo *cluster); static void check_for_not_null_inheritance(ClusterInfo *cluster); static void check_for_gist_inet_ops(ClusterInfo *cluster); -static void check_for_pg_role_prefix(ClusterInfo *cluster); static void check_for_new_tablespace_dir(void); static void check_for_user_defined_encoding_conversions(ClusterInfo *cluster); static void check_for_unicode_update(ClusterInfo *cluster); @@ -128,26 +127,6 @@ static DataTypesUsageChecks data_types_usage_checks[] = .threshold_version = ALL_VERSIONS }, - /* - * 9.3 -> 9.4 Fully implement the 'line' data type in 9.4, which - * previously returned "not enabled" by default and was only functionally - * enabled with a compile-time switch; as of 9.4 "line" has a different - * on-disk representation format. - */ - { - .status = gettext_noop("Checking for incompatible \"line\" data type"), - .report_filename = "tables_using_line.txt", - .base_query = - "SELECT 'pg_catalog.line'::pg_catalog.regtype AS oid", - .report_text = - gettext_noop("Your installation contains the \"line\" data type in user tables.\n" - "This data type changed its internal and input/output format\n" - "between your old and new versions so this\n" - "cluster cannot currently be upgraded. You can\n" - "drop the problem columns and restart the upgrade.\n"), - .threshold_version = 903 - }, - /* * pg_upgrade only preserves these system values: pg_class.oid pg_type.oid * pg_enum.oid @@ -209,30 +188,6 @@ static DataTypesUsageChecks data_types_usage_checks[] = .threshold_version = 1500 }, - /* - * It's no longer allowed to create tables or views with "unknown"-type - * columns. We do not complain about views with such columns, because - * they should get silently converted to "text" columns during the DDL - * dump and reload; it seems unlikely to be worth making users do that by - * hand. However, if there's a table with such a column, the DDL reload - * will fail, so we should pre-detect that rather than failing - * mid-upgrade. Worse, if there's a matview with such a column, the DDL - * reload will silently change it to "text" which won't match the on-disk - * storage (which is like "cstring"). So we *must* reject that. - */ - { - .status = gettext_noop("Checking for invalid \"unknown\" user columns"), - .report_filename = "tables_using_unknown.txt", - .base_query = - "SELECT 'pg_catalog.unknown'::pg_catalog.regtype AS oid", - .report_text = - gettext_noop("Your installation contains the \"unknown\" data type in user tables.\n" - "This data type is no longer allowed in tables, so this cluster\n" - "cannot currently be upgraded. You can drop the problem columns\n" - "and restart the upgrade.\n"), - .threshold_version = 906 - }, - /* * PG 12 changed the 'sql_identifier' type storage to be based on name, * not varchar, which breaks on-disk format for existing data. So we need @@ -255,23 +210,6 @@ static DataTypesUsageChecks data_types_usage_checks[] = .threshold_version = 1100 }, - /* - * JSONB changed its storage format during 9.4 beta, so check for it. - */ - { - .status = gettext_noop("Checking for incompatible \"jsonb\" data type in user tables"), - .report_filename = "tables_using_jsonb.txt", - .base_query = - "SELECT 'pg_catalog.jsonb'::pg_catalog.regtype AS oid", - .report_text = - gettext_noop("Your installation contains the \"jsonb\" data type in user tables.\n" - "The internal format of \"jsonb\" changed during 9.4 beta so this\n" - "cluster cannot currently be upgraded. You can drop the problem \n" - "columns and restart the upgrade.\n"), - .threshold_version = MANUAL_CHECK, - .version_hook = jsonb_9_4_check_applicable - }, - /* * PG 12 removed types abstime, reltime, tinterval. */ @@ -712,20 +650,6 @@ check_and_dump_old_cluster(void) if (GET_MAJOR_VERSION(old_cluster.major_version) <= 1800) check_for_gist_inet_ops(&old_cluster); - /* - * Pre-PG 10 allowed tables with 'unknown' type columns and non WAL logged - * hash indexes - */ - if (GET_MAJOR_VERSION(old_cluster.major_version) <= 906) - { - if (user_opts.check) - old_9_6_invalidate_hash_indexes(&old_cluster, true); - } - - /* 9.5 and below should not have roles starting with pg_ */ - if (GET_MAJOR_VERSION(old_cluster.major_version) <= 905) - check_for_pg_role_prefix(&old_cluster); - /* * While not a check option, we do this now because this is the only time * the old server is running. @@ -772,20 +696,6 @@ check_new_cluster(void) * system boundaries. */ check_hard_link(TRANSFER_MODE_SWAP); - - /* - * There are a few known issues with using --swap to upgrade from - * versions older than 10. For example, the sequence tuple format - * changed in v10, and the visibility map format changed in 9.6. - * While such problems are not insurmountable (and we may have to - * deal with similar problems in the future, anyway), it doesn't - * seem worth the effort to support swap mode for upgrades from - * long-unsupported versions. - */ - if (GET_MAJOR_VERSION(old_cluster.major_version) < 1000) - pg_fatal("Swap mode can only upgrade clusters from PostgreSQL version %s and later.", - "10"); - break; } @@ -831,10 +741,6 @@ issue_warnings_and_set_wal_level(void) */ start_postmaster(&new_cluster, true); - /* Reindex hash indexes for old < 10.0 */ - if (GET_MAJOR_VERSION(old_cluster.major_version) <= 906) - old_9_6_invalidate_hash_indexes(&new_cluster, false); - report_extension_updates(&new_cluster); stop_postmaster(false); @@ -892,9 +798,9 @@ check_cluster_versions(void) * upgrades */ - if (GET_MAJOR_VERSION(old_cluster.major_version) < 902) + if (GET_MAJOR_VERSION(old_cluster.major_version) < 10) pg_fatal("This utility can only upgrade from PostgreSQL version %s and later.", - "9.2"); + "10"); /* Only current PG version is supported as a target */ if (GET_MAJOR_VERSION(new_cluster.major_version) != GET_MAJOR_VERSION(PG_VERSION_NUM)) @@ -1569,12 +1475,10 @@ check_for_incompatible_polymorphics(ClusterInfo *cluster) ", 'array_cat(anyarray,anyarray)'" ", 'array_prepend(anyelement,anyarray)'"); - if (GET_MAJOR_VERSION(cluster->major_version) >= 903) appendPQExpBufferStr(&old_polymorphics, ", 'array_remove(anyarray,anyelement)'" ", 'array_replace(anyarray,anyelement,anyelement)'"); - if (GET_MAJOR_VERSION(cluster->major_version) >= 905) appendPQExpBufferStr(&old_polymorphics, ", 'array_position(anyarray,anyelement)'" ", 'array_position(anyarray,anyelement,integer)'" @@ -1870,63 +1774,6 @@ check_for_gist_inet_ops(ClusterInfo *cluster) check_ok(); } -/* - * check_for_pg_role_prefix() - * - * Versions older than 9.6 should not have any pg_* roles - */ -static void -check_for_pg_role_prefix(ClusterInfo *cluster) -{ - PGresult *res; - PGconn *conn = connectToServer(cluster, "template1"); - int ntups; - int i_roloid; - int i_rolname; - FILE *script = NULL; - char output_path[MAXPGPATH]; - - prep_status("Checking for roles starting with \"pg_\""); - - snprintf(output_path, sizeof(output_path), "%s/%s", - log_opts.basedir, - "pg_role_prefix.txt"); - - res = executeQueryOrDie(conn, - "SELECT oid AS roloid, rolname " - "FROM pg_catalog.pg_roles " - "WHERE rolname ~ '^pg_'"); - - ntups = PQntuples(res); - i_roloid = PQfnumber(res, "roloid"); - i_rolname = PQfnumber(res, "rolname"); - for (int rowno = 0; rowno < ntups; rowno++) - { - if (script == NULL && (script = fopen_priv(output_path, "w")) == NULL) - pg_fatal("could not open file \"%s\": %m", output_path); - fprintf(script, "%s (oid=%s)\n", - PQgetvalue(res, rowno, i_rolname), - PQgetvalue(res, rowno, i_roloid)); - } - - PQclear(res); - - PQfinish(conn); - - if (script) - { - fclose(script); - pg_log(PG_REPORT, "fatal"); - pg_fatal("Your installation contains roles starting with \"pg_\".\n" - "\"pg_\" is a reserved prefix for system roles. The cluster\n" - "cannot be upgraded until these roles are renamed.\n" - "A list of roles starting with \"pg_\" is in the file:\n" - " %s", output_path); - } - else - check_ok(); -} - /* * Callback function for processing results of query for * check_for_user_defined_encoding_conversions()'s UpgradeTask. If the query diff --git a/src/bin/pg_upgrade/controldata.c b/src/bin/pg_upgrade/controldata.c index cffcd4b0eba..8188355240f 100644 --- a/src/bin/pg_upgrade/controldata.c +++ b/src/bin/pg_upgrade/controldata.c @@ -602,14 +602,12 @@ get_control_data(ClusterInfo *cluster) /* verify that we got all the mandatory pg_control data */ if (!got_xid || !got_oid || !got_multi || !got_oldestxid || - (!got_oldestmulti && - cluster->controldata.cat_ver >= MULTIXACT_FORMATCHANGE_CAT_VER) || + !got_oldestmulti || !got_mxoff || (!live_check && !got_nextxlogfile) || !got_float8_pass_by_value || !got_align || !got_blocksz || !got_largesz || !got_walsz || !got_walseg || !got_ident || !got_index || !got_toast || - (!got_large_object && - cluster->controldata.ctrl_ver >= LARGE_OBJECT_SIZE_PG_CONTROL_VER) || + !got_large_object || !got_date_is_int || !got_data_checksum_version || (!got_default_char_signedness && cluster->controldata.cat_ver >= DEFAULT_CHAR_SIGNEDNESS_CAT_VER)) @@ -630,8 +628,7 @@ get_control_data(ClusterInfo *cluster) if (!got_multi) pg_log(PG_REPORT, " latest checkpoint next MultiXactId"); - if (!got_oldestmulti && - cluster->controldata.cat_ver >= MULTIXACT_FORMATCHANGE_CAT_VER) + if (!got_oldestmulti) pg_log(PG_REPORT, " latest checkpoint oldest MultiXactId"); if (!got_oldestxid) @@ -670,8 +667,7 @@ get_control_data(ClusterInfo *cluster) if (!got_toast) pg_log(PG_REPORT, " maximum TOAST chunk size"); - if (!got_large_object && - cluster->controldata.ctrl_ver >= LARGE_OBJECT_SIZE_PG_CONTROL_VER) + if (!got_large_object) pg_log(PG_REPORT, " large-object chunk size"); if (!got_date_is_int) diff --git a/src/bin/pg_upgrade/exec.c b/src/bin/pg_upgrade/exec.c index e1de61f36ee..479557abdcc 100644 --- a/src/bin/pg_upgrade/exec.c +++ b/src/bin/pg_upgrade/exec.c @@ -55,16 +55,7 @@ get_bin_version(ClusterInfo *cluster) if (sscanf(cmd_output, "%*s %*s %d.%d", &v1, &v2) < 1) pg_fatal("could not get pg_ctl version output from %s", cmd); - if (v1 < 10) - { - /* old style, e.g. 9.6.1 */ - cluster->bin_version = v1 * 10000 + v2 * 100; - } - else - { - /* new style, e.g. 10.1 */ cluster->bin_version = v1 * 10000; - } } @@ -353,17 +344,7 @@ check_data_dir(ClusterInfo *cluster) check_single_dir(pg_data, "pg_subtrans"); check_single_dir(pg_data, PG_TBLSPC_DIR); check_single_dir(pg_data, "pg_twophase"); - - /* pg_xlog has been renamed to pg_wal in v10 */ - if (GET_MAJOR_VERSION(cluster->major_version) <= 906) - check_single_dir(pg_data, "pg_xlog"); - else check_single_dir(pg_data, "pg_wal"); - - /* pg_clog has been renamed to pg_xact in v10 */ - if (GET_MAJOR_VERSION(cluster->major_version) <= 906) - check_single_dir(pg_data, "pg_clog"); - else check_single_dir(pg_data, "pg_xact"); } @@ -404,10 +385,6 @@ check_bin_dir(ClusterInfo *cluster, bool check_versions) */ get_bin_version(cluster); - /* pg_resetxlog has been renamed to pg_resetwal in version 10 */ - if (GET_MAJOR_VERSION(cluster->bin_version) <= 906) - check_exec(cluster->bindir, "pg_resetxlog", check_versions); - else check_exec(cluster->bindir, "pg_resetwal", check_versions); if (cluster == &new_cluster) diff --git a/src/bin/pg_upgrade/file.c b/src/bin/pg_upgrade/file.c index 5b276008614..af82c0de490 100644 --- a/src/bin/pg_upgrade/file.c +++ b/src/bin/pg_upgrade/file.c @@ -20,12 +20,8 @@ #include <linux/fs.h> #endif -#include "access/visibilitymapdefs.h" #include "common/file_perm.h" #include "pg_upgrade.h" -#include "storage/bufpage.h" -#include "storage/checksum.h" -#include "storage/checksum_impl.h" /* @@ -196,166 +192,6 @@ linkFile(const char *src, const char *dst, } -/* - * rewriteVisibilityMap() - * - * Transform a visibility map file, copying from src to dst. - * schemaName/relName are relation's SQL name (used for error messages only). - * - * In versions of PostgreSQL prior to catversion 201603011, PostgreSQL's - * visibility map included one bit per heap page; it now includes two. - * When upgrading a cluster from before that time to a current PostgreSQL - * version, we could refuse to copy visibility maps from the old cluster - * to the new cluster; the next VACUUM would recreate them, but at the - * price of scanning the entire table. So, instead, we rewrite the old - * visibility maps in the new format. That way, the all-visible bits - * remain set for the pages for which they were set previously. The - * all-frozen bits are never set by this conversion; we leave that to VACUUM. - */ -void -rewriteVisibilityMap(const char *fromfile, const char *tofile, - const char *schemaName, const char *relName) -{ - int src_fd; - int dst_fd; - PGIOAlignedBlock buffer; - PGIOAlignedBlock new_vmbuf; - ssize_t totalBytesRead = 0; - ssize_t src_filesize; - int rewriteVmBytesPerPage; - BlockNumber new_blkno = 0; - struct stat statbuf; - - /* Compute number of old-format bytes per new page */ - rewriteVmBytesPerPage = (BLCKSZ - SizeOfPageHeaderData) / 2; - - if ((src_fd = open(fromfile, O_RDONLY | PG_BINARY, 0)) < 0) - pg_fatal("error while copying relation \"%s.%s\": could not open file \"%s\": %m", - schemaName, relName, fromfile); - - if (fstat(src_fd, &statbuf) != 0) - pg_fatal("error while copying relation \"%s.%s\": could not stat file \"%s\": %m", - schemaName, relName, fromfile); - - if ((dst_fd = open(tofile, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, - pg_file_create_mode)) < 0) - pg_fatal("error while copying relation \"%s.%s\": could not create file \"%s\": %m", - schemaName, relName, tofile); - - /* Save old file size */ - src_filesize = statbuf.st_size; - - /* - * Turn each visibility map page into 2 pages one by one. Each new page - * has the same page header as the old one. If the last section of the - * last page is empty, we skip it, mostly to avoid turning one-page - * visibility maps for small relations into two pages needlessly. - */ - while (totalBytesRead < src_filesize) - { - ssize_t bytesRead; - char *old_cur; - char *old_break; - char *old_blkend; - PageHeaderData pageheader; - bool old_lastblk; - - if ((bytesRead = read(src_fd, buffer.data, BLCKSZ)) != BLCKSZ) - { - if (bytesRead < 0) - pg_fatal("error while copying relation \"%s.%s\": could not read file \"%s\": %m", - schemaName, relName, fromfile); - else - pg_fatal("error while copying relation \"%s.%s\": partial page found in file \"%s\"", - schemaName, relName, fromfile); - } - - totalBytesRead += BLCKSZ; - old_lastblk = (totalBytesRead == src_filesize); - - /* Save the page header data */ - memcpy(&pageheader, buffer.data, SizeOfPageHeaderData); - - /* - * These old_* variables point to old visibility map page. old_cur - * points to current position on old page. old_blkend points to end of - * old block. old_break is the end+1 position on the old page for the - * data that will be transferred to the current new page. - */ - old_cur = buffer.data + SizeOfPageHeaderData; - old_blkend = buffer.data + bytesRead; - old_break = old_cur + rewriteVmBytesPerPage; - - while (old_break <= old_blkend) - { - char *new_cur; - bool empty = true; - bool old_lastpart; - - /* First, copy old page header to new page */ - memcpy(new_vmbuf.data, &pageheader, SizeOfPageHeaderData); - - /* Rewriting the last part of the last old page? */ - old_lastpart = old_lastblk && (old_break == old_blkend); - - new_cur = new_vmbuf.data + SizeOfPageHeaderData; - - /* Process old page bytes one by one, and turn it into new page. */ - while (old_cur < old_break) - { - uint8 byte = *(uint8 *) old_cur; - uint16 new_vmbits = 0; - int i; - - /* Generate new format bits while keeping old information */ - for (i = 0; i < BITS_PER_BYTE; i++) - { - if (byte & (1 << i)) - { - empty = false; - new_vmbits |= - VISIBILITYMAP_ALL_VISIBLE << (BITS_PER_HEAPBLOCK * i); - } - } - - /* Copy new visibility map bytes to new-format page */ - new_cur[0] = (char) (new_vmbits & 0xFF); - new_cur[1] = (char) (new_vmbits >> 8); - - old_cur++; - new_cur += BITS_PER_HEAPBLOCK; - } - - /* If the last part of the last page is empty, skip writing it */ - if (old_lastpart && empty) - break; - - /* Set new checksum for visibility map page, if enabled */ - if (new_cluster.controldata.data_checksum_version != PG_DATA_CHECKSUM_OFF) - ((PageHeader) new_vmbuf.data)->pd_checksum = - pg_checksum_page(new_vmbuf.data, new_blkno); - - errno = 0; - if (write(dst_fd, new_vmbuf.data, BLCKSZ) != BLCKSZ) - { - /* if write didn't set errno, assume problem is no disk space */ - if (errno == 0) - errno = ENOSPC; - pg_fatal("error while copying relation \"%s.%s\": could not write file \"%s\": %m", - schemaName, relName, tofile); - } - - /* Advance for next new page */ - old_break += rewriteVmBytesPerPage; - new_blkno++; - } - } - - /* Clean up */ - close(dst_fd); - close(src_fd); -} - void check_file_clone(void) { diff --git a/src/bin/pg_upgrade/multixact_rewrite.c b/src/bin/pg_upgrade/multixact_rewrite.c index 823984ec8f3..c45b3183684 100644 --- a/src/bin/pg_upgrade/multixact_rewrite.c +++ b/src/bin/pg_upgrade/multixact_rewrite.c @@ -25,10 +25,7 @@ static void RecordMultiXactMembers(SlruSegState *members_writer, * 32-bit offsets to the current format. * * Multixids in the range [from_multi, to_multi) are read from the old - * cluster, and written in the new format. An important edge case is that if - * from_multi == to_multi, this initializes the new pg_multixact files in the - * new format without trying to open any old files. (We rely on that when - * upgrading from PostgreSQL version 9.2 or below.) + * cluster, and written in the new format. * * Returns the new nextOffset value; the caller should set it in the new * control file. The new members always start from offset 1, regardless of @@ -42,6 +39,7 @@ rewrite_multixacts(MultiXactId from_multi, MultiXactId to_multi) SlruSegState *members_writer; char dir[MAXPGPATH] = {0}; bool prev_multixid_valid = false; + OldMultiXactReader *old_reader; /* * The range of valid multi XIDs is unchanged by the conversion (they are @@ -63,10 +61,6 @@ rewrite_multixacts(MultiXactId from_multi, MultiXactId to_multi) * Convert old multixids, if needed, by reading them one-by-one from the * old cluster. */ - if (to_multi != from_multi) - { - OldMultiXactReader *old_reader; - old_reader = AllocOldMultiXactRead(old_cluster.pgdata, old_cluster.controldata.chkpnt_nxtmulti, old_cluster.controldata.chkpnt_nxtmxoff); @@ -113,7 +107,6 @@ rewrite_multixacts(MultiXactId from_multi, MultiXactId to_multi) } FreeOldMultiXactReader(old_reader); - } /* Write the final 'next' offset to the last SLRU page */ RecordMultiXactOffset(offsets_writer, to_multi, diff --git a/src/bin/pg_upgrade/pg_upgrade.c b/src/bin/pg_upgrade/pg_upgrade.c index 2127d297bfe..e5d7920c1b1 100644 --- a/src/bin/pg_upgrade/pg_upgrade.c +++ b/src/bin/pg_upgrade/pg_upgrade.c @@ -714,13 +714,6 @@ create_new_objects(void) end_progress_output(); check_ok(); - /* - * We don't have minmxids for databases or relations in pre-9.3 clusters, - * so set those after we have restored the schema. - */ - if (GET_MAJOR_VERSION(old_cluster.major_version) <= 902) - set_frozenxids(true); - /* update new_cluster info now that we have objects in the databases */ get_db_rel_and_slot_infos(&new_cluster); } @@ -777,10 +770,7 @@ copy_xact_xlog_xid(void) * Copy old commit logs to new data dir. pg_clog has been renamed to * pg_xact in post-10 clusters. */ - copy_subdir_files(GET_MAJOR_VERSION(old_cluster.major_version) <= 906 ? - "pg_clog" : "pg_xact", - GET_MAJOR_VERSION(new_cluster.major_version) <= 906 ? - "pg_clog" : "pg_xact"); + copy_subdir_files("pg_xact", "pg_xact"); prep_status("Setting oldest XID for new cluster"); exec_prog(UTILITY_LOG_FILE, NULL, true, true, @@ -809,7 +799,6 @@ copy_xact_xlog_xid(void) check_ok(); /* Copy or convert pg_multixact files */ - Assert(new_cluster.controldata.cat_ver >= MULTIXACT_FORMATCHANGE_CAT_VER); Assert(new_cluster.controldata.cat_ver >= MULTIXACTOFFSET_FORMATCHANGE_CAT_VER); if (old_cluster.controldata.cat_ver >= MULTIXACTOFFSET_FORMATCHANGE_CAT_VER) { @@ -844,25 +833,7 @@ copy_xact_xlog_xid(void) * Determine the range of multixacts to convert. */ nxtmulti = old_cluster.controldata.chkpnt_nxtmulti; - if (old_cluster.controldata.cat_ver >= MULTIXACT_FORMATCHANGE_CAT_VER) - { - /* Versions 9.3 - 18: convert all multixids */ oldstMulti = old_cluster.controldata.chkpnt_oldstMulti; - } - else - { - /* - * In PostgreSQL 9.2 and below, multitransactions were only used - * for row locking, and as such don't need to be preserved during - * upgrade. In that case, we utilize rewrite_multixacts() just to - * initialize new, empty files in the new format. - * - * It's important that the oldest multi is set to the latest value - * used by the old system, so that multixact.c returns the empty - * set for multis that might be present on disk. - */ - oldstMulti = nxtmulti; - } /* handle wraparound */ if (nxtmulti < FirstMultiXactId) nxtmulti = FirstMultiXactId; diff --git a/src/bin/pg_upgrade/pg_upgrade.h b/src/bin/pg_upgrade/pg_upgrade.h index 1d767bbda2d..5a0d2045be5 100644 --- a/src/bin/pg_upgrade/pg_upgrade.h +++ b/src/bin/pg_upgrade/pg_upgrade.h @@ -101,19 +101,6 @@ extern char *output_files[]; #endif -/* - * The format of visibility map was changed with this 9.6 commit. - */ -#define VISIBILITY_MAP_FROZEN_BIT_CAT_VER 201603011 - -/* - * pg_multixact format changed in 9.3 commit 0ac5ad5134f2769ccbaefec73844f85, - * ("Improve concurrency of foreign key locking") which also updated catalog - * version to this value. pg_upgrade behavior depends on whether old and new - * server versions are both newer than this, or only the new one is. - */ -#define MULTIXACT_FORMATCHANGE_CAT_VER 201301231 - /* * MultiXactOffset was changed from 32-bit to 64-bit in version 19, at this * catalog version. pg_multixact files need to be converted when upgrading @@ -121,17 +108,6 @@ extern char *output_files[]; */ #define MULTIXACTOFFSET_FORMATCHANGE_CAT_VER 202512091 -/* - * large object chunk size added to pg_controldata, - * commit 5f93c37805e7485488480916b4585e098d3cc883 - */ -#define LARGE_OBJECT_SIZE_PG_CONTROL_VER 942 - -/* - * change in JSONB format during 9.4 beta - */ -#define JSONB_FORMAT_CHANGE_CAT_VER 201409291 - /* * The control file was changed to have the default char signedness, * commit 44fe30fdab6746a287163e7cc093fd36cda8eb92 @@ -429,8 +405,6 @@ void copyFileByRange(const char *src, const char *dst, const char *schemaName, const char *relName); void linkFile(const char *src, const char *dst, const char *schemaName, const char *relName); -void rewriteVisibilityMap(const char *fromfile, const char *tofile, - const char *schemaName, const char *relName); void check_file_clone(void); void check_copy_file_range(void); void check_hard_link(transferMode transfer_mode); @@ -500,10 +474,7 @@ unsigned int str2uint(const char *str); /* version.c */ -bool jsonb_9_4_check_applicable(ClusterInfo *cluster); bool protocol_negotiation_supported(const ClusterInfo *cluster); -void old_9_6_invalidate_hash_indexes(ClusterInfo *cluster, - bool check_mode); void report_extension_updates(ClusterInfo *cluster); diff --git a/src/bin/pg_upgrade/relfilenumber.c b/src/bin/pg_upgrade/relfilenumber.c index d5088447e0d..ec2ff7acb21 100644 --- a/src/bin/pg_upgrade/relfilenumber.c +++ b/src/bin/pg_upgrade/relfilenumber.c @@ -18,7 +18,7 @@ #include "pg_upgrade.h" static void transfer_single_new_db(FileNameMap *maps, int size, char *old_tablespace, char *new_tablespace); -static void transfer_relfile(FileNameMap *map, const char *type_suffix, bool vm_must_add_frozenbit); +static void transfer_relfile(FileNameMap *map, const char *type_suffix); /* * The following set of sync_queue_* functions are used for --swap to reduce @@ -496,25 +496,10 @@ transfer_single_new_db(FileNameMap *maps, int size, char *old_tablespace, char *new_tablespace) { int mapnum; - bool vm_must_add_frozenbit = false; - - /* - * Do we need to rewrite visibilitymap? - */ - if (old_cluster.controldata.cat_ver < VISIBILITY_MAP_FROZEN_BIT_CAT_VER && - new_cluster.controldata.cat_ver >= VISIBILITY_MAP_FROZEN_BIT_CAT_VER) - vm_must_add_frozenbit = true; /* --swap has its own subroutine */ if (user_opts.transfer_mode == TRANSFER_MODE_SWAP) { - /* - * We don't support --swap to upgrade from versions that require - * rewriting the visibility map. We should've failed already if - * someone tries to do that. - */ - Assert(!vm_must_add_frozenbit); - do_swap(maps, size, old_tablespace, new_tablespace); return; } @@ -525,13 +510,13 @@ transfer_single_new_db(FileNameMap *maps, int size, strcmp(maps[mapnum].old_tablespace, old_tablespace) == 0) { /* transfer primary file */ - transfer_relfile(&maps[mapnum], "", vm_must_add_frozenbit); + transfer_relfile(&maps[mapnum], ""); /* * Copy/link any fsm and vm files, if they exist */ - transfer_relfile(&maps[mapnum], "_fsm", vm_must_add_frozenbit); - transfer_relfile(&maps[mapnum], "_vm", vm_must_add_frozenbit); + transfer_relfile(&maps[mapnum], "_fsm"); + transfer_relfile(&maps[mapnum], "_vm"); } } } @@ -540,12 +525,10 @@ transfer_single_new_db(FileNameMap *maps, int size, /* * transfer_relfile() * - * Copy or link file from old cluster to new one. If vm_must_add_frozenbit - * is true, visibility map forks are converted and rewritten, even in link - * mode. + * Copy or link file from old cluster to new one. */ static void -transfer_relfile(FileNameMap *map, const char *type_suffix, bool vm_must_add_frozenbit) +transfer_relfile(FileNameMap *map, const char *type_suffix) { char old_file[MAXPGPATH]; char new_file[MAXPGPATH]; @@ -604,14 +587,6 @@ transfer_relfile(FileNameMap *map, const char *type_suffix, bool vm_must_add_fro /* Copying files might take some time, so give feedback. */ pg_log(PG_STATUS, "%s", old_file); - if (vm_must_add_frozenbit && strcmp(type_suffix, "_vm") == 0) - { - /* Need to rewrite visibility map format */ - pg_log(PG_VERBOSE, "rewriting \"%s\" to \"%s\"", - old_file, new_file); - rewriteVisibilityMap(old_file, new_file, map->nspname, map->relname); - } - else switch (user_opts.transfer_mode) { case TRANSFER_MODE_CLONE: diff --git a/src/bin/pg_upgrade/version.c b/src/bin/pg_upgrade/version.c index 047670d4acb..9e83d4659be 100644 --- a/src/bin/pg_upgrade/version.c +++ b/src/bin/pg_upgrade/version.c @@ -12,22 +12,6 @@ #include "fe_utils/string_utils.h" #include "pg_upgrade.h" -/* - * version_hook functions for check_for_data_types_usage in order to determine - * whether a data type check should be executed for the cluster in question or - * not. - */ -bool -jsonb_9_4_check_applicable(ClusterInfo *cluster) -{ - /* JSONB changed its storage format during 9.4 beta */ - if (GET_MAJOR_VERSION(cluster->major_version) == 904 && - cluster->controldata.cat_ver < JSONB_FORMAT_CHANGE_CAT_VER) - return true; - - return false; -} - /* * Older servers can't support newer protocol versions, so their connection * strings will need to lock max_protocol_version to 3.0. @@ -46,117 +30,6 @@ protocol_negotiation_supported(const ClusterInfo *cluster) return (GET_MAJOR_VERSION(cluster->major_version) >= 1100); } -/* - * old_9_6_invalidate_hash_indexes() - * 9.6 -> 10 - * Hash index binary format has changed from 9.6->10.0 - */ -void -old_9_6_invalidate_hash_indexes(ClusterInfo *cluster, bool check_mode) -{ - int dbnum; - FILE *script = NULL; - bool found = false; - char *output_path = "reindex_hash.sql"; - - prep_status("Checking for hash indexes"); - - for (dbnum = 0; dbnum < cluster->dbarr.ndbs; dbnum++) - { - PGresult *res; - bool db_used = false; - int ntups; - int rowno; - int i_nspname, - i_relname; - DbInfo *active_db = &cluster->dbarr.dbs[dbnum]; - PGconn *conn = connectToServer(cluster, active_db->db_name); - - /* find hash indexes */ - res = executeQueryOrDie(conn, - "SELECT n.nspname, c.relname " - "FROM pg_catalog.pg_class c, " - " pg_catalog.pg_index i, " - " pg_catalog.pg_am a, " - " pg_catalog.pg_namespace n " - "WHERE i.indexrelid = c.oid AND " - " c.relam = a.oid AND " - " c.relnamespace = n.oid AND " - " a.amname = 'hash'" - ); - - ntups = PQntuples(res); - i_nspname = PQfnumber(res, "nspname"); - i_relname = PQfnumber(res, "relname"); - for (rowno = 0; rowno < ntups; rowno++) - { - found = true; - if (!check_mode) - { - if (script == NULL && (script = fopen_priv(output_path, "w")) == NULL) - pg_fatal("could not open file \"%s\": %m", output_path); - if (!db_used) - { - PQExpBufferData connectbuf; - - initPQExpBuffer(&connectbuf); - appendPsqlMetaConnect(&connectbuf, active_db->db_name); - fputs(connectbuf.data, script); - termPQExpBuffer(&connectbuf); - db_used = true; - } - fprintf(script, "REINDEX INDEX %s.%s;\n", - quote_identifier(PQgetvalue(res, rowno, i_nspname)), - quote_identifier(PQgetvalue(res, rowno, i_relname))); - } - } - - PQclear(res); - - if (!check_mode && db_used) - { - /* mark hash indexes as invalid */ - PQclear(executeQueryOrDie(conn, - "UPDATE pg_catalog.pg_index i " - "SET indisvalid = false " - "FROM pg_catalog.pg_class c, " - " pg_catalog.pg_am a, " - " pg_catalog.pg_namespace n " - "WHERE i.indexrelid = c.oid AND " - " c.relam = a.oid AND " - " c.relnamespace = n.oid AND " - " a.amname = 'hash'")); - } - - PQfinish(conn); - } - - if (script) - fclose(script); - - if (found) - { - report_status(PG_WARNING, "warning"); - if (check_mode) - pg_log(PG_WARNING, "\n" - "Your installation contains hash indexes. These indexes have different\n" - "internal formats between your old and new clusters, so they must be\n" - "reindexed with the REINDEX command. After upgrading, you will be given\n" - "REINDEX instructions."); - else - pg_log(PG_WARNING, "\n" - "Your installation contains hash indexes. These indexes have different\n" - "internal formats between your old and new clusters, so they must be\n" - "reindexed with the REINDEX command. The file\n" - " %s\n" - "when executed by psql by the database superuser will recreate all invalid\n" - "indexes; until then, none of these indexes will be used.", - output_path); - } - else - check_ok(); -} - /* * Callback function for processing results of query for * report_extension_updates()'s UpgradeTask. If the query returned any rows, -- 2.50.1 (Apple Git-155) --CT89ko5pLUrsvFtH Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v2-0003-psql-bump-minimum-supported-version-to-v10.patch ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
* [PATCH v16 2/2] handle relation statistics correctly during rewrites @ 2026-05-18 15:20 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 571+ messages in thread From: Bertrand Drouvot @ 2026-05-18 15:20 UTC (permalink / raw) This patch ensures that relation statistics are preserved correctly when a relation is rewritten (e.g., during CLUSTER, VACUUM FULL, ALTER TABLE operations that require a table rewrite, or TRUNCATE). Since patch 0001 keys PGSTAT_KIND_RELATION by the physical RelFileLocator rather than the relation OID, a rewrite (which assigns a new relfilenode) would lose the accumulated statistics if not handled specially. The approach is: 1. When a rewrite occurs (RelationSetNewRelfilenumber or swap_relation_files), record the old and new locators via pgstat_mark_rewrite(). 2. During pgstat_assoc_relation(), if the relation's new locator matches a pending rewrite, continue using the stats entry associated with the old locator. This ensures stats accumulated after the rewrite are still tracked in the original entry. 3. At transaction commit (AtEOXact_PgStat_Relations), process pending rewrites: flush any pending stats for the old locator, copy them to the new locator's stats entry, and drop the old entry. 4. At subtransaction abort, remove rewrites from the aborted nesting level. 5. For two-phase transactions, the rewrite information is recorded in the TwoPhasePgStatRecord and replayed at commit/abort time. This also handles chained rewrites (multiple rewrites of the same relation in a single transaction) by tracking the original locator through the chain. --- src/backend/catalog/index.c | 2 +- src/backend/commands/repack.c | 5 + src/backend/commands/tablecmds.c | 6 + src/backend/utils/activity/pgstat_relation.c | 392 ++++++++++++++++++- src/backend/utils/activity/pgstat_xact.c | 25 +- src/backend/utils/cache/relcache.c | 6 + src/include/pgstat.h | 5 +- src/tools/pgindent/typedefs.list | 1 + 8 files changed, 425 insertions(+), 17 deletions(-) 92.8% src/backend/utils/activity/ 4.8% src/backend/ diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9407c357f27..335ff1e50f6 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1813,7 +1813,7 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName) changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId); /* copy over statistics from old to new index */ - pgstat_copy_relation_stats(newClassRel, oldClassRel); + pgstat_copy_relation_stats(newClassRel->rd_locator, oldClassRel->rd_locator, false); /* Copy data of pg_statistic from the old index to the new one */ CopyStatistics(oldIndexId, newIndexId); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 351a3cc32e8..eda4135bcd1 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -1633,6 +1633,11 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, rel1 = relation_open(r1, NoLock); rel2 = relation_open(r2, NoLock); + + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel1->rd_rel->relkind)) + pgstat_mark_rewrite(rel1->rd_locator, rel2->rd_locator); + rel2->rd_createSubid = rel1->rd_createSubid; rel2->rd_newRelfilelocatorSubid = rel1->rd_newRelfilelocatorSubid; rel2->rd_firstRelfilelocatorSubid = rel1->rd_firstRelfilelocatorSubid; diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 92b0f38c353..b553b9a4970 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17129,6 +17129,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) Oid reltoastrelid; RelFileNumber newrelfilenumber; RelFileLocator newrlocator; + RelFileLocator oldrlocator; List *reltoastidxids = NIL; ListCell *lc; @@ -17167,6 +17168,7 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) newrlocator = rel->rd_locator; newrlocator.relNumber = newrelfilenumber; newrlocator.spcOid = newTableSpace; + oldrlocator = rel->rd_locator; /* hand off to AM to actually create new rel storage and copy the data */ if (rel->rd_rel->relkind == RELKIND_INDEX) @@ -17179,6 +17181,10 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode) table_relation_copy_data(rel, &newrlocator); } + /* mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Update the pg_class row. * diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c index 7fcda7f7518..18d1b9fc59d 100644 --- a/src/backend/utils/activity/pgstat_relation.c +++ b/src/backend/utils/activity/pgstat_relation.c @@ -30,6 +30,19 @@ #include "utils/syscache.h" #include "utils/timestamp.h" +/* Pending rewrite operations for stats copying */ +typedef struct PgStat_PendingRewrite +{ + RelFileLocator old_locator; + RelFileLocator new_locator; + RelFileLocator original_locator; + int nest_level; /* Transaction nesting level where rewrite + * occurred */ + struct PgStat_PendingRewrite *next; +} PgStat_PendingRewrite; + +/* The pending rewrites list for current transaction */ +static PgStat_PendingRewrite *pending_rewrites = NULL; /* Record that's written to 2PC state file when pgstat state is persisted */ typedef struct TwoPhasePgStatRecord @@ -43,6 +56,8 @@ typedef struct TwoPhasePgStatRecord PgStat_Counter deleted_pre_truncdrop; RelFileLocator locator; /* table's rd_locator */ bool truncdropped; /* was the relation truncated/dropped? */ + RelFileLocator rewrite_old_locator; + int rewrite_nest_level; } TwoPhasePgStatRecord; @@ -54,27 +69,71 @@ static void restore_truncdrop_counters(PgStat_TableXactStatus *trans); /* - * Copy stats between relations. This is used for things like REINDEX + * Copy stats between RelFileLocator. This is used for things like REINDEX * CONCURRENTLY. */ void -pgstat_copy_relation_stats(Relation dst, Relation src) +pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment) { PgStat_StatTabEntry *srcstats; PgStatShared_Relation *dstshstats; PgStat_EntryRef *dst_ref; - srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src), NULL); + srcstats = (PgStat_StatTabEntry *) pgstat_fetch_entry(PGSTAT_KIND_RELATION, + src.dbOid, + RelFileLocatorToPgStatObjid(src), + NULL); if (!srcstats) return; dst_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, - dst->rd_rel->relisshared ? InvalidOid : MyDatabaseId, - RelationGetRelid(dst), + dst.dbOid, + RelFileLocatorToPgStatObjid(dst), false); dstshstats = (PgStatShared_Relation *) dst_ref->shared_stats; - dstshstats->stats = *srcstats; + + if (!increment) + dstshstats->stats = *srcstats; + else + { + /* Increment those statistics */ +#define RELFSTAT_ACC(fld, stats_to_add) \ + (dstshstats->stats.fld += stats_to_add->fld) + RELFSTAT_ACC(numscans, srcstats); + RELFSTAT_ACC(tuples_returned, srcstats); + RELFSTAT_ACC(tuples_fetched, srcstats); + RELFSTAT_ACC(tuples_inserted, srcstats); + RELFSTAT_ACC(tuples_updated, srcstats); + RELFSTAT_ACC(tuples_deleted, srcstats); + RELFSTAT_ACC(tuples_hot_updated, srcstats); + RELFSTAT_ACC(tuples_newpage_updated, srcstats); + RELFSTAT_ACC(live_tuples, srcstats); + RELFSTAT_ACC(dead_tuples, srcstats); + RELFSTAT_ACC(mod_since_analyze, srcstats); + RELFSTAT_ACC(ins_since_vacuum, srcstats); + RELFSTAT_ACC(blocks_fetched, srcstats); + RELFSTAT_ACC(blocks_hit, srcstats); + RELFSTAT_ACC(vacuum_count, srcstats); + RELFSTAT_ACC(autovacuum_count, srcstats); + RELFSTAT_ACC(analyze_count, srcstats); + RELFSTAT_ACC(autoanalyze_count, srcstats); + RELFSTAT_ACC(total_vacuum_time, srcstats); + RELFSTAT_ACC(total_autovacuum_time, srcstats); + RELFSTAT_ACC(total_analyze_time, srcstats); + RELFSTAT_ACC(total_autoanalyze_time, srcstats); +#undef RELFSTAT_ACC + + /* Replace those statistics */ +#define RELFSTAT_REP(fld, stats_to_rep) \ + (dstshstats->stats.fld = stats_to_rep->fld) + RELFSTAT_REP(lastscan, srcstats); + RELFSTAT_REP(last_vacuum_time, srcstats); + RELFSTAT_REP(last_autovacuum_time, srcstats); + RELFSTAT_REP(last_analyze_time, srcstats); + RELFSTAT_REP(last_autoanalyze_time, srcstats); +#undef RELFSTAT_REP + } pgstat_unlock_entry(dst_ref); } @@ -136,6 +195,7 @@ void pgstat_assoc_relation(Relation rel) { RelFileLocator locator; + PgStat_TableStatus *pgstat_info; Assert(rel->pgstat_enabled); Assert(rel->pgstat_info == NULL); @@ -164,14 +224,54 @@ pgstat_assoc_relation(Relation rel) locator.relNumber = rel->rd_id; } + /* + * If this relation was rewritten during the current transaction we may be + * reopening it with its new RelFileLocator. In that case, continue using + * the stats entry associated with the old locator rather than creating a + * new one. This ensures all stats from before and after the rewrite are + * tracked in a single entry which will be properly copied to the new + * locator at transaction commit. + */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (locator.dbOid == rewrite->new_locator.dbOid && + locator.spcOid == rewrite->new_locator.spcOid && + locator.relNumber == rewrite->new_locator.relNumber) + { + pgstat_info = pgstat_prep_relation_pending(rewrite->old_locator); + goto found_entry; + } + } + } + /* Else find or make the PgStat_TableStatus entry, and update link */ - rel->pgstat_info = pgstat_prep_relation_pending(locator); + pgstat_info = pgstat_prep_relation_pending(locator); + +found_entry: + rel->pgstat_info = pgstat_info; + + /* + * For relations stats, we key by physical file location, not by relation + * OID. This means during operations like ALTER TYPE it's possible that + * the relation OID changes but the relfilenode stays the same (no actual + * rewrite needed). Unlink the old relation first. + */ + if (pgstat_info->relation != NULL && + pgstat_info->relation != rel) + { + pgstat_info->relation->pgstat_info = NULL; + pgstat_info->relation = NULL; + } /* don't allow link a stats to multiple relcache entries */ - Assert(rel->pgstat_info->relation == NULL); + Assert(pgstat_info->relation == NULL); /* mark this relation as the owner */ - rel->pgstat_info->relation = rel; + pgstat_info->relation = rel; } /* @@ -214,14 +314,37 @@ pgstat_drop_relation(Relation rel) { int nest_level = GetCurrentTransactionNestLevel(); PgStat_TableStatus *pgstat_info; + bool skip_transactional_drop = false; /* don't track stats for relations without storage */ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind)) return; - pgstat_drop_transactional(PGSTAT_KIND_RELATION, - rel->rd_locator.dbOid, - RelFileLocatorToPgStatObjid(rel->rd_locator)); + /* Check if this drop is part of a pending rewrite */ + if (pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + if (rel->rd_locator.dbOid == rewrite->old_locator.dbOid && + rel->rd_locator.spcOid == rewrite->old_locator.spcOid && + rel->rd_locator.relNumber == rewrite->old_locator.relNumber) + { + skip_transactional_drop = true; + break; + } + } + } + + /* + * If it is part of a rewrite, drop its stats later, for example in + * AtEOXact_PgStat_Relations(), so skip it here. + */ + if (!skip_transactional_drop) + pgstat_drop_transactional(PGSTAT_KIND_RELATION, + rel->rd_locator.dbOid, + RelFileLocatorToPgStatObjid(rel->rd_locator)); if (!pgstat_should_count_relation(rel)) return; @@ -668,6 +791,48 @@ AtEOXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit) } tabstat->trans = NULL; } + + /* preserve the stats in case of rewrite */ + if (isCommit && pending_rewrites != NULL) + { + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *prev = NULL; + PgStat_PendingRewrite *current = pending_rewrites; + PgStat_PendingRewrite *next; + + /* reverse the rewrites list to process in chronological order */ + while (current != NULL) + { + next = current->next; + current->next = prev; + prev = current; + current = next; + } + + /* now process rewrites in chronological order */ + for (rewrite = prev; rewrite != NULL; rewrite = rewrite->next) + { + PgStat_EntryRef *old_entry_ref; + + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + pgstat_copy_relation_stats(rewrite->new_locator, + rewrite->old_locator, true); + + /* drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rewrite->old_locator.dbOid, + RelFileLocatorToPgStatObjid(rewrite->old_locator))) + pgstat_request_entry_refs_gc(); + } + } + + pending_rewrites = NULL; } /* @@ -683,6 +848,30 @@ AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool isCommit, in PgStat_TableXactStatus *trans; PgStat_TableXactStatus *next_trans; + /* + * If we don't commit then remove the associated rewrites if any, to keep + * the rewrite chain in sync with what will be eventually committed. + */ + if (!isCommit) + { + PgStat_PendingRewrite **rewrite_ptr = &pending_rewrites; + + while (*rewrite_ptr != NULL) + { + if ((*rewrite_ptr)->nest_level >= nestDepth) + { + PgStat_PendingRewrite *to_remove = *rewrite_ptr; + + *rewrite_ptr = (*rewrite_ptr)->next; + pfree(to_remove); + } + else + { + rewrite_ptr = &((*rewrite_ptr)->next); + } + } + } + for (trans = xact_state->first; trans != NULL; trans = next_trans) { PgStat_TableStatus *tabstat; @@ -762,11 +951,19 @@ void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) { PgStat_TableXactStatus *trans; + PgStat_PendingRewrite *rewrite; + /* + * For each tabstat, find its matching rewrite and remove it from the + * pending rewrites list. This way, after processing all tabstats, pending + * rewrites will only contain rewrite only transactions. + */ for (trans = xact_state->first; trans != NULL; trans = trans->next) { PgStat_TableStatus *tabstat PG_USED_FOR_ASSERTS_ONLY; TwoPhasePgStatRecord record; + PgStat_PendingRewrite **rewrite_ptr; + bool found_rewrite = false; Assert(trans->nest_level == 1); Assert(trans->upper == NULL); @@ -786,10 +983,83 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) record.locator = tabstat->locator; record.truncdropped = trans->truncdropped; + record.rewrite_nest_level = 0; + + /* + * Look for a matching rewrite and remove it from pending rewrites. We + * check three possible matches: + * + * The new_locator when stats have been added after the rewrite. The + * old_locator when stats have been added before the rewrite but not + * after. The original_locator when this tabstat is part of a rewrite + * chain. + */ + rewrite_ptr = &pending_rewrites; + while (*rewrite_ptr != NULL) + { + rewrite = *rewrite_ptr; + + if ((record.locator.dbOid == rewrite->new_locator.dbOid && + record.locator.spcOid == rewrite->new_locator.spcOid && + record.locator.relNumber == rewrite->new_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->old_locator.dbOid && + tabstat->locator.spcOid == rewrite->old_locator.spcOid && + tabstat->locator.relNumber == rewrite->old_locator.relNumber) || + (tabstat->locator.dbOid == rewrite->original_locator.dbOid && + tabstat->locator.spcOid == rewrite->original_locator.spcOid && + tabstat->locator.relNumber == rewrite->original_locator.relNumber)) + { + /* + * Found matching rewrite. Record the rewrite information and + * remove this rewrite from the list since it's now handled. + */ + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.locator = rewrite->new_locator; + found_rewrite = true; + + /* Remove from pending_rewrites list */ + *rewrite_ptr = rewrite->next; + pfree(rewrite); + break; + } + else + { + /* Move to next rewrite in the list */ + rewrite_ptr = &(rewrite->next); + } + } + + /* If no rewrite found, clear the rewrite fields */ + if (!found_rewrite) + { + memset(&record.rewrite_old_locator, 0, sizeof(RelFileLocator)); + } + + RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, + &record, sizeof(TwoPhasePgStatRecord)); + } + + /* + * Now process any rewrites still pending. These are rewrite only + * transactions. We need to preserve their stats even though there's no + * tabstat entry for them. + */ + for (rewrite = pending_rewrites; rewrite != NULL; rewrite = rewrite->next) + { + TwoPhasePgStatRecord record; + + memset(&record, 0, sizeof(TwoPhasePgStatRecord)); + record.locator = rewrite->new_locator; + record.rewrite_old_locator = rewrite->original_locator; + record.rewrite_nest_level = rewrite->nest_level; + record.truncdropped = false; RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0, &record, sizeof(TwoPhasePgStatRecord)); } + + pending_rewrites = NULL; } /* @@ -812,6 +1082,8 @@ PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state) tabstat = trans->parent; tabstat->trans = NULL; } + + pending_rewrites = NULL; } /* @@ -847,6 +1119,29 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info, pgstat_info->counts.changed_tuples += rec->tuples_inserted + rec->tuples_updated + rec->tuples_deleted; + + if (rec->rewrite_nest_level > 0) + { + PgStat_EntryRef *old_entry_ref; + + /* Flush any pending stats for old locator first */ + old_entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator)); + + if (old_entry_ref && old_entry_ref->pending) + pgstat_relation_flush_cb(old_entry_ref, false); + + /* Copy stats from old to new locator */ + pgstat_copy_relation_stats(rec->locator, rec->rewrite_old_locator, + true); + + /* Drop old locator's stats */ + if (!pgstat_drop_entry(PGSTAT_KIND_RELATION, + rec->rewrite_old_locator.dbOid, + RelFileLocatorToPgStatObjid(rec->rewrite_old_locator))) + pgstat_request_entry_refs_gc(); + } } /* @@ -861,9 +1156,26 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info, { TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata; PgStat_TableStatus *pgstat_info; + RelFileLocator target_locator; + + /* + * For aborted transactions with rewrites (like TRUNCATE), we need to + * restore stats to the old locator, not the new one. The new locator + * should be dropped since the rewrite is being rolled back. + */ + if (rec->rewrite_nest_level > 0) + { + /* Use the old locator */ + target_locator = rec->rewrite_old_locator; + } + else + { + /* No rewrite, use the original locator */ + target_locator = rec->locator; + } /* Find or create a tabstat entry for the target locator */ - pgstat_info = pgstat_prep_relation_pending(rec->locator); + pgstat_info = pgstat_prep_relation_pending(target_locator); /* Same math as in AtEOXact_PgStat, abort case */ if (rec->truncdropped) @@ -918,7 +1230,17 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait) tabentry->numscans += lstats->counts.numscans; if (lstats->counts.numscans) { - TimestampTz t = GetCurrentTransactionStopTimestamp(); + TimestampTz t; + + /* + * Checking the transaction state due to the flush call in + * pgstat_twophase_postcommit() that would break the assertion on the + * state in GetCurrentTransactionStopTimestamp(). + */ + if (!IsTransactionState()) + t = GetCurrentTransactionStopTimestamp(); + else + t = GetCurrentTimestamp(); if (t > tabentry->lastscan) tabentry->lastscan = t; @@ -1169,3 +1491,45 @@ pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator) ReleaseSysCache(tuple); return result; } + +/* + * Mark that a relation rewrite has occurred, preserving the original locator + * so stats can be copied at transaction commit. + */ +void +pgstat_mark_rewrite(RelFileLocator old_locator, RelFileLocator new_locator) +{ + PgStat_PendingRewrite *rewrite; + PgStat_PendingRewrite *existing; + RelFileLocator original_locator = old_locator; + + for (existing = pending_rewrites; existing != NULL; existing = existing->next) + { + if (old_locator.dbOid == existing->new_locator.dbOid && + old_locator.spcOid == existing->new_locator.spcOid && + old_locator.relNumber == existing->new_locator.relNumber) + { + original_locator = existing->original_locator; + break; + } + } + + /* Allocate in TopTransactionContext memory context */ + rewrite = MemoryContextAlloc(TopTransactionContext, + sizeof(PgStat_PendingRewrite)); + + rewrite->old_locator = old_locator; + rewrite->new_locator = new_locator; + rewrite->original_locator = original_locator; + rewrite->nest_level = GetCurrentTransactionNestLevel(); + + /* Add to the list */ + rewrite->next = pending_rewrites; + pending_rewrites = rewrite; +} + +void +pgstat_clear_rewrite(void) +{ + pending_rewrites = NULL; +} diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c index 5e2d69e6297..8ed8f5317f3 100644 --- a/src/backend/utils/activity/pgstat_xact.c +++ b/src/backend/utils/activity/pgstat_xact.c @@ -55,6 +55,8 @@ AtEOXact_PgStat(bool isCommit, bool parallel) } pgStatXactStack = NULL; + pgstat_clear_rewrite(); + /* Make sure any stats snapshot is thrown away */ pgstat_clear_snapshot(); } @@ -360,8 +362,29 @@ create_drop_transactional_internal(PgStat_Kind kind, Oid dboid, uint64 objid, bo void pgstat_create_transactional(PgStat_Kind kind, Oid dboid, uint64 objid) { - if (pgstat_get_entry_ref(kind, dboid, objid, false, NULL)) + PgStat_EntryRef *entry_ref; + + entry_ref = pgstat_get_entry_ref(kind, dboid, objid, false, NULL); + + if (entry_ref) { + /* + * For relations stats, we key by physical file location, not by + * relation OID. This means during operations like ALTER TYPE where + * the relation OID changes but the relfilenode stays the same (no + * actual rewrite needed), we'll find an existing entry. + * + * This is expected behavior, we want to preserve stats across the + * catalog change. Simply reset and recreate the entry for the new + * relation OID without warning. + */ + if (kind == PGSTAT_KIND_RELATION) + { + pgstat_reset(kind, dboid, objid); + create_drop_transactional_internal(kind, dboid, objid, true); + return; + } + ereport(WARNING, errmsg("resetting existing statistics for kind %s, db=%u, oid=%" PRIu64, (pgstat_get_kind_info(kind))->name, dboid, diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 0572ab424e7..d84058db102 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -87,6 +87,7 @@ #include "utils/inval.h" #include "utils/lsyscache.h" #include "utils/memutils.h" +#include "utils/pgstat_internal.h" #include "utils/relmapper.h" #include "utils/resowner.h" #include "utils/snapmgr.h" @@ -3782,6 +3783,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) MultiXactId minmulti = InvalidMultiXactId; TransactionId freezeXid = InvalidTransactionId; RelFileLocator newrlocator; + RelFileLocator oldrlocator = relation->rd_locator; if (!IsBinaryUpgrade) { @@ -3953,6 +3955,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) table_close(pg_class, RowExclusiveLock); + /* Mark that a rewrite happened */ + if (RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) + pgstat_mark_rewrite(oldrlocator, newrlocator); + /* * Make the pg_class row change or relation map change visible. This will * cause the relcache entry to get updated, too. diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 941a39bd16e..5344ece9ecf 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -697,7 +697,7 @@ extern PgStat_FunctionCounts *find_funcstat_entry(Oid func_id); extern void pgstat_create_relation(Relation rel); extern void pgstat_drop_relation(Relation rel); -extern void pgstat_copy_relation_stats(Relation dst, Relation src); +extern void pgstat_copy_relation_stats(RelFileLocator dst, RelFileLocator src, bool increment); extern void pgstat_init_relation(Relation rel); extern void pgstat_assoc_relation(Relation rel); @@ -709,6 +709,9 @@ extern void pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples, extern void pgstat_report_analyze(Relation rel, PgStat_Counter livetuples, PgStat_Counter deadtuples, bool resetcounter, TimestampTz starttime); +extern void pgstat_mark_rewrite(RelFileLocator old_locator, + RelFileLocator new_locator); +extern void pgstat_clear_rewrite(void); /* * If stats are enabled, but pending data hasn't been prepared yet, call diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 8cf40c87043..1544f54e918 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2349,6 +2349,7 @@ PgStat_LockEntry PgStat_PendingDroppedStatsItem PgStat_PendingIO PgStat_PendingLock +PgStat_PendingRewrite PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1 --Uc+t0mng6H5VV2zk-- ^ permalink raw reply [nested|flat] 571+ messages in thread
end of thread, other threads:[~2026-05-18 15:20 UTC | newest] Thread overview: 571+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v14 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v11 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v8 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v12 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v15 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v13 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v10 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v9 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2025-11-04 13:52 [PATCH v7 3/3] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-04-17 18:20 [PATCH v2 2/4] pg_upgrade: bump minimum supported version to v10 Nathan Bossart <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]> 2026-05-18 15:20 [PATCH v16 2/2] handle relation statistics correctly during rewrites Bertrand Drouvot <[email protected]>
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